/*

    SDL_rotozoom.c

    Copyright (C) A. Schiffler, July 2001

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

*/

#ifdef WIN32
#include <windows.h>
#endif

#include <stdlib.h>
#include <string.h>

#include "SDL_rotozoom.h"

#define MAX(a,b)    (((a) > (b)) ? (a) : (b))

/*

 32bit Zoomer with optional anti-aliasing by bilinear interpolation.

 Zoomes 32bit RGBA/ABGR 'src' surface to 'dst' surface.

*/

int
zoomSurfaceRGBA (SDL_Surface * src, SDL_Surface * dst, int smooth)
{
  int x, y, sx, sy, *sax, *say, *csax, *csay, csx, csy, ex, ey, t1, t2, sstep;
  tColorRGBA *c00, *c01, *c10, *c11;
  tColorRGBA *sp, *csp, *dp;
  int sgap, dgap, orderRGBA;

  /* Variable setup */
  if (smooth)
    {
      /* For interpolation: assume source dimension is one pixel */
      /* smaller to avoid overflow on right and bottom edge.     */
      sx = (int) (65536.0 * (float) (src->w - 1) / (float) dst->w);
      sy = (int) (65536.0 * (float) (src->h - 1) / (float) dst->h);
    }
  else
    {
      sx = (int) (65536.0 * (float) src->w / (float) dst->w);
      sy = (int) (65536.0 * (float) src->h / (float) dst->h);
    }

  /* Allocate memory for row increments */
  if ((sax = (int *) malloc ((dst->w + 1) * sizeof (Uint32))) == NULL)
    {
      return (-1);
    }
  if ((say = (int *) malloc ((dst->h + 1) * sizeof (Uint32))) == NULL)
    {
      free (sax);
      return (-1);
    }

  /* Precalculate row increments */
  csx = 0;
  csax = sax;
  for (x = 0; x <= dst->w; x++)
    {
      *csax = csx;
      csax++;
      csx &= 0xffff;
      csx += sx;
    }
  csy = 0;
  csay = say;
  for (y = 0; y <= dst->h; y++)
    {
      *csay = csy;
      csay++;
      csy &= 0xffff;
      csy += sy;
    }

  /* Pointer setup */
  sp = csp = (tColorRGBA *) src->pixels;
  dp = (tColorRGBA *) dst->pixels;
  sgap = src->pitch - src->w * 4;
  dgap = dst->pitch - dst->w * 4;
  orderRGBA = (src->format->Rmask == 0x000000ff);

  /* Switch between interpolating and non-interpolating code */
  if (smooth)
    {

      /* Interpolating Zoom */

      /* Scan destination */
      csay = say;
      for (y = 0; y < dst->h; y++)
	{
	  /* Setup color source pointers */
	  c00 = csp;
	  c01 = csp;
	  c01++;
	  c10 = (tColorRGBA *) ((Uint8 *) csp + src->pitch);
	  c11 = c10;
	  c11++;
	  csax = sax;
	  for (x = 0; x < dst->w; x++)
	    {
	      /* ABGR ordering */
	      /* Interpolate colors */
	      ex = (*csax & 0xffff);
	      ey = (*csay & 0xffff);
	      t1 = ((((c01->r - c00->r) * ex) >> 16) + c00->r) & 0xff;
	      t2 = ((((c11->r - c10->r) * ex) >> 16) + c10->r) & 0xff;
	      dp->r = (((t2 - t1) * ey) >> 16) + t1;
	      t1 = ((((c01->g - c00->g) * ex) >> 16) + c00->g) & 0xff;
	      t2 = ((((c11->g - c10->g) * ex) >> 16) + c10->g) & 0xff;
	      dp->g = (((t2 - t1) * ey) >> 16) + t1;
	      t1 = ((((c01->b - c00->b) * ex) >> 16) + c00->b) & 0xff;
	      t2 = ((((c11->b - c10->b) * ex) >> 16) + c10->b) & 0xff;
	      dp->b = (((t2 - t1) * ey) >> 16) + t1;
	      t1 = ((((c01->a - c00->a) * ex) >> 16) + c00->a) & 0xff;
	      t2 = ((((c11->a - c10->a) * ex) >> 16) + c10->a) & 0xff;
	      dp->a = (((t2 - t1) * ey) >> 16) + t1;
	      /* Advance source pointers */
	      csax++;
	      sstep = (*csax >> 16);
	      c00 += sstep;
	      c01 += sstep;
	      c10 += sstep;
	      c11 += sstep;
	      /* Advance destination pointer */
	      dp++;
	    }
	  /* Advance source pointer */
	  csay++;
	  csp = (tColorRGBA *) ((Uint8 *) csp + (*csay >> 16) * src->pitch);
	  /* Advance destination pointers */
	  dp = (tColorRGBA *) ((Uint8 *) dp + dgap);
	}

    }
  else
    {

      /* Non-Interpolating Zoom */

      csay = say;
      for (y = 0; y < dst->h; y++)
	{
	  sp = csp;
	  csax = sax;
	  for (x = 0; x < dst->w; x++)
	    {
	      /* Draw */
	      *dp = *sp;
	      /* Advance source pointers */
	      csax++;
	      sp += (*csax >> 16);
	      /* Advance destination pointer */
	      dp++;
	    }
	  /* Advance source pointer */
	  csay++;
	  csp = (tColorRGBA *) ((Uint8 *) csp + (*csay >> 16) * src->pitch);
	  /* Advance destination pointers */
	  dp = (tColorRGBA *) ((Uint8 *) dp + dgap);
	}

    }

  /* Remove temp arrays */
  free (sax);
  free (say);

  return (0);
}

/*

 8bit Zoomer without smoothing.

 Zoomes 8bit palette/Y 'src' surface to 'dst' surface.

*/

int
zoomSurfaceY (SDL_Surface * src, SDL_Surface * dst)
{
  Uint32 x, y, sx, sy, *sax, *say, *csax, *csay, csx, csy;
  Uint8 *sp, *dp, *csp;
  int dgap;

  /* Variable setup */
  sx = (Uint32) (65536.0 * (float) src->w / (float) dst->w);
  sy = (Uint32) (65536.0 * (float) src->h / (float) dst->h);

  /* Allocate memory for row increments */
  if ((sax = (Uint32 *) malloc (dst->w * sizeof (Uint32))) == NULL)
    {
      return (-1);
    }
  if ((say = (Uint32 *) malloc (dst->h * sizeof (Uint32))) == NULL)
    {
      if (sax != NULL)
	{
	  free (sax);
	}
      return (-1);
    }

  /* Precalculate row increments */
  csx = 0;
  csax = sax;
  for (x = 0; x < dst->w; x++)
    {
      csx += sx;
      *csax = (csx >> 16);
      csx &= 0xffff;
      csax++;
    }
  csy = 0;
  csay = say;
  for (y = 0; y < dst->h; y++)
    {
      csy += sy;
      *csay = (csy >> 16);
      csy &= 0xffff;
      csay++;
    }

  csx = 0;
  csax = sax;
  for (x = 0; x < dst->w; x++)
    {
      csx += (*csax);
      csax++;
    }
  csy = 0;
  csay = say;
  for (y = 0; y < dst->h; y++)
    {
      csy += (*csay);
      csay++;
    }

  /* Pointer setup */
  sp = csp = (Uint8 *) src->pixels;
  dp = (Uint8 *) dst->pixels;
  dgap = dst->pitch - dst->w;

  /* Draw */
  csay = say;
  for (y = 0; y < dst->h; y++)
    {
      csax = sax;
      sp = csp;
      for (x = 0; x < dst->w; x++)
	{
	  /* Draw */
	  *dp = *sp;
	  /* Advance source pointers */
	  sp += (*csax);
	  csax++;
	  /* Advance destination pointer */
	  dp++;
	}
      /* Advance source pointer (for row) */
      csp += ((*csay) * src->pitch);
      csay++;
      /* Advance destination pointers */
      dp += dgap;
    }

  /* Remove temp arrays */
  free (sax);
  free (say);

  return (0);
}

/*

 32bit Rotozoomer with optional anti-aliasing by bilinear interpolation.

 Rotates and zoomes 32bit RGBA/ABGR 'src' surface to 'dst' surface.

*/

void
transformSurfaceRGBA (SDL_Surface * src, SDL_Surface * dst, int cx, int cy,
		      int isin, int icos, int smooth)
{
  int x, y, t1, t2, dx, dy, xd, yd, sdx, sdy, ax, ay, ex, ey, sw, sh;
  tColorRGBA c00, c01, c10, c11;
  tColorRGBA *pc, *sp;
  int gap, orderRGBA;

  /* Variable setup */
  xd = ((src->w - dst->w) << 15);
  yd = ((src->h - dst->h) << 15);
  ax = (cx << 16) - (icos * cx);
  ay = (cy << 16) - (isin * cx);
  sw = src->w - 1;
  sh = src->h - 1;
  pc = dst->pixels;
  gap = dst->pitch - dst->w * 4;
  orderRGBA = (src->format->Rmask == 0x000000ff);

  /* Switch between interpolating and non-interpolating code */
  if (smooth)
    {
      for (y = 0; y < dst->h; y++)
	{
	  dy = cy - y;
	  sdx = (ax + (isin * dy)) + xd;
	  sdy = (ay - (icos * dy)) + yd;
	  for (x = 0; x < dst->w; x++)
	    {
	      dx = (sdx >> 16);
	      dy = (sdy >> 16);
	      if ((dx >= -1) && (dy >= -1) && (dx < src->w) && (dy < src->h))
		{
		  if ((dx >= 0) && (dy >= 0) && (dx < sw) && (dy < sh))
		    {
		      sp =
			(tColorRGBA *) ((Uint8 *) src->pixels +
					src->pitch * dy);
		      sp += dx;
		      c00 = *sp;
		      sp += 1;
		      c01 = *sp;
		      sp = (tColorRGBA *) ((Uint8 *) sp + src->pitch);
		      sp -= 1;
		      c10 = *sp;
		      sp += 1;
		      c11 = *sp;
		    }
		  else if ((dx == sw) && (dy == sh))
		    {
		      sp =
			(tColorRGBA *) ((Uint8 *) src->pixels +
					src->pitch * dy);
		      sp += dx;
		      c00 = *sp;
		      c01 = *pc;
		      c10 = *pc;
		      c11 = *pc;
		    }
		  else if ((dx == -1) && (dy == -1))
		    {
		      sp = (tColorRGBA *) (src->pixels);
		      c00 = *pc;
		      c01 = *pc;
		      c10 = *pc;
		      c11 = *sp;
		    }
		  else if ((dx == -1) && (dy == sh))
		    {
		      sp = (tColorRGBA *) (src->pixels);
		      sp =
			(tColorRGBA *) ((Uint8 *) src->pixels +
					src->pitch * dy);
		      c00 = *pc;
		      c01 = *sp;
		      c10 = *pc;
		      c11 = *pc;
		    }
		  else if ((dx == sw) && (dy == -1))
		    {
		      sp = (tColorRGBA *) (src->pixels);
		      sp += dx;
		      c00 = *pc;
		      c01 = *pc;
		      c10 = *sp;
		      c11 = *pc;
		    }
		  else if (dx == -1)
		    {
		      sp =
			(tColorRGBA *) ((Uint8 *) src->pixels +
					src->pitch * dy);
		      c00 = *pc;
		      c01 = *sp;
		      c10 = *pc;
		      sp = (tColorRGBA *) ((Uint8 *) sp + src->pitch);
		      c11 = *sp;
		    }
		  else if (dy == -1)
		    {
		      sp = (tColorRGBA *) (src->pixels);
		      sp += dx;
		      c00 = *pc;
		      c01 = *pc;
		      c10 = *sp;
		      sp += 1;
		      c11 = *sp;
		    }
		  else if (dx == sw)
		    {
		      sp =
			(tColorRGBA *) ((Uint8 *) src->pixels +
					src->pitch * dy);
		      sp += dx;
		      c00 = *sp;
		      c01 = *pc;
		      sp = (tColorRGBA *) ((Uint8 *) sp + src->pitch);
		      c10 = *sp;
		      c11 = *pc;
		    }
		  else if (dy == sh)
		    {
		      sp =
			(tColorRGBA *) ((Uint8 *) src->pixels +
					src->pitch * dy);
		      sp += dx;
		      c00 = *sp;
		      sp += 1;
		      c01 = *sp;
		      c10 = *pc;
		      c11 = *pc;
		    }
		  /* Interpolate colors */
		  ex = (sdx & 0xffff);
		  ey = (sdy & 0xffff);
		  t1 = ((((c01.r - c00.r) * ex) >> 16) + c00.r) & 0xff;
		  t2 = ((((c11.r - c10.r) * ex) >> 16) + c10.r) & 0xff;
		  pc->r = (((t2 - t1) * ey) >> 16) + t1;
		  t1 = ((((c01.g - c00.g) * ex) >> 16) + c00.g) & 0xff;
		  t2 = ((((c11.g - c10.g) * ex) >> 16) + c10.g) & 0xff;
		  pc->g = (((t2 - t1) * ey) >> 16) + t1;
		  t1 = ((((c01.b - c00.b) * ex) >> 16) + c00.b) & 0xff;
		  t2 = ((((c11.b - c10.b) * ex) >> 16) + c10.b) & 0xff;
		  pc->b = (((t2 - t1) * ey) >> 16) + t1;
		  t1 = ((((c01.a - c00.a) * ex) >> 16) + c00.a) & 0xff;
		  t2 = ((((c11.a - c10.a) * ex) >> 16) + c10.a) & 0xff;
		  pc->a = (((t2 - t1) * ey) >> 16) + t1;

		}
	      sdx += icos;
	      sdy += isin;
	      pc++;
	    }
	  pc = (tColorRGBA *) ((Uint8 *) pc + gap);
	}
    }
  else
    {
      for (y = 0; y < dst->h; y++)
	{
	  dy = cy - y;
	  sdx = (ax + (isin * dy)) + xd;
	  sdy = (ay - (icos * dy)) + yd;
	  for (x = 0; x < dst->w; x++)
	    {
	      dx = (short) (sdx >> 16);
	      dy = (short) (sdy >> 16);
	      if ((dx >= 0) && (dy >= 0) && (dx < src->w) && (dy < src->h))
		{
		  sp =
		    (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
		  sp += dx;
		  *pc = *sp;
		}
	      sdx += icos;
	      sdy += isin;
	      pc++;
	    }
	  pc = (tColorRGBA *) ((Uint8 *) pc + gap);
	}
    }
}

/*

 8bit Rotozoomer without smoothing

 Rotates and zoomes 8bit palette/Y 'src' surface to 'dst' surface.

*/

void
transformSurfaceY (SDL_Surface * src, SDL_Surface * dst, int cx, int cy,
		   int isin, int icos)
{
  int x, y, dx, dy, xd, yd, sdx, sdy, ax, ay, sw, sh;
  tColorY *pc, *sp;
  int gap;

  /* Variable setup */
  xd = ((src->w - dst->w) << 15);
  yd = ((src->h - dst->h) << 15);
  ax = (cx << 16) - (icos * cx);
  ay = (cy << 16) - (isin * cx);
  sw = src->w - 1;
  sh = src->h - 1;
  pc = dst->pixels;
  gap = dst->pitch - dst->w;
  /* Clear surface to colorkey */
  memset (pc, (unsigned char) (src->format->colorkey & 0xff),
	  dst->pitch * dst->h);
  /* Iterate through destination surface */
  for (y = 0; y < dst->h; y++)
    {
      dy = cy - y;
      sdx = (ax + (isin * dy)) + xd;
      sdy = (ay - (icos * dy)) + yd;
      for (x = 0; x < dst->w; x++)
	{
	  dx = (short) (sdx >> 16);
	  dy = (short) (sdy >> 16);
	  if ((dx >= 0) && (dy >= 0) && (dx < src->w) && (dy < src->h))
	    {
	      sp = (tColorY *) (src->pixels);
	      sp += (src->pitch * dy + dx);
	      *pc = *sp;
	    }
	  sdx += icos;
	  sdy += isin;
	  pc++;
	}
      pc += gap;
    }
}

/*

 rotozoomSurface()

 Rotates and zoomes a 32bit or 8bit 'src' surface to newly created 'dst' surface.
 'angle' is the rotation in degrees. 'zoom' a scaling factor. If 'smooth' is 1
 then the destination 32bit surface is anti-aliased. If the surface is not 8bit
 or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly.

*/

#define VALUE_LIMIT	0.001

SDL_Surface *
rotozoomSurface (SDL_Surface * src, double angle, double zoom, int smooth)
{
  SDL_Surface *rz_src;
  SDL_Surface *rz_dst;
  double zoominv;
  double radangle, sanglezoom, canglezoom, sanglezoominv, canglezoominv;
  int dstwidthhalf, dstwidth, dstheighthalf, dstheight;
  double x, y, cx, cy, sx, sy;
  int is32bit;
  int i, src_converted;

  /* Sanity check */
  if (src == NULL)
    return (NULL);

  /* Determine if source surface is 32bit or 8bit */
  is32bit = (src->format->BitsPerPixel == 32);
  if ((is32bit) || (src->format->BitsPerPixel == 8))
    {
      /* Use source surface 'as is' */
      rz_src = src;
      src_converted = 0;
    }
  else
    {
      /* New source surface is 32bit with a defined RGBA ordering */
      rz_src =
	SDL_CreateRGBSurface (SDL_SWSURFACE | SDL_SRCALPHA, src->w, src->h, 32, 0x000000ff,
			      0x0000ff00, 0x00ff0000, 0xff000000);
      SDL_BlitSurface (src, NULL, rz_src, NULL);
      src_converted = 1;
      is32bit = 1;
    }

  /* Sanity check zoom factor */
  if (zoom < VALUE_LIMIT)
    {
      zoom = VALUE_LIMIT;
    }
  zoominv = 65536.0 / zoom;

  /* Check if we have a rotozoom or just a zoom */
  if (fabs (angle) > VALUE_LIMIT)
    {

      /* Angle!=0: full rotozoom */
      /* ----------------------- */

      /* Calculate target factors from sin/cos and zoom */
      radangle = angle * (M_PI / 180.0);
      sanglezoom = sanglezoominv = sin (radangle);
      canglezoom = canglezoominv = cos (radangle);
      sanglezoom *= zoom;
      canglezoom *= zoom;
      sanglezoominv *= zoominv;
      canglezoominv *= zoominv;

      /* Determine destination width and height by rotating a centered source box */
      x = rz_src->w / 2;
      y = rz_src->h / 2;
      cx = canglezoom * x;
      cy = canglezoom * y;
      sx = sanglezoom * x;
      sy = sanglezoom * y;
      dstwidthhalf =
	MAX ((int)
	     ceil (MAX
		   (MAX
		    (MAX (fabs (cx + sy), fabs (cx - sy)), fabs (-cx + sy)),
		    fabs (-cx - sy))), 1);
      dstheighthalf =
	MAX ((int)
	     ceil (MAX
		   (MAX
		    (MAX (fabs (sx + cy), fabs (sx - cy)), fabs (-sx + cy)),
		    fabs (-sx - cy))), 1);
      dstwidth = 2 * dstwidthhalf;
      dstheight = 2 * dstheighthalf;

      /* Alloc space to completely contain the rotated surface */
      rz_dst = NULL;
      if (is32bit)
	{
	  /* Target surface is 32bit with source RGBA/ABGR ordering */
	  rz_dst =
	    SDL_CreateRGBSurface (SDL_SWSURFACE | SDL_SRCALPHA, dstwidth, dstheight, 32,
				  rz_src->format->Rmask,
				  rz_src->format->Gmask,
				  rz_src->format->Bmask,
				  rz_src->format->Amask);
	}
      else
	{
	  /* Target surface is 8bit */
	  rz_dst =
	    SDL_CreateRGBSurface (SDL_SWSURFACE , dstwidth, dstheight, 8, 0, 0,
				  0, 0);
	}

      /* Lock source surface */
      SDL_LockSurface (rz_src);
      /* Check which kind of surface we have */
      if (is32bit)
	{
	  /* Call the 32bit transformation routine to do the rotation (using alpha) */
	  transformSurfaceRGBA (rz_src, rz_dst, dstwidthhalf, dstheighthalf,
				(int) (sanglezoominv),
				(int) (canglezoominv), smooth);
	  /* Turn on source-alpha support */
	  SDL_SetAlpha (rz_dst, SDL_SRCALPHA, 255);
	}
      else
	{
	  /* Copy palette and colorkey info */
	  for (i = 0; i < rz_src->format->palette->ncolors; i++)
	    {
	      rz_dst->format->palette->colors[i] =
		rz_src->format->palette->colors[i];
	    }
	  rz_dst->format->palette->ncolors = rz_src->format->palette->ncolors;
	  /* Call the 8bit transformation routine to do the rotation */
	  transformSurfaceY (rz_src, rz_dst, dstwidthhalf, dstheighthalf,
			     (int) (sanglezoominv), (int) (canglezoominv));
	  SDL_SetColorKey (rz_dst, SDL_SRCCOLORKEY | SDL_RLEACCEL,
			   rz_src->format->colorkey);
	}
      /* Unlock source surface */
      SDL_UnlockSurface (rz_src);

    }
  else
    {

      /* Angle=0: Just a zoom */
      /* -------------------- */

      /* Calculate target size and set rect */
      dstwidth = (int) ((double) rz_src->w * zoom);
      dstheight = (int) ((double) rz_src->h * zoom);
      if (dstwidth < 1)
	{
	  dstwidth = 1;
	}
      if (dstheight < 1)
	{
	  dstheight = 1;
	}

      /* Alloc space to completely contain the zoomed surface */
      rz_dst = NULL;
      if (is32bit)
	{
	  /* Target surface is 32bit with source RGBA/ABGR ordering */
	  rz_dst =
	    SDL_CreateRGBSurface (SDL_SWSURFACE, dstwidth, dstheight, 32,
				  rz_src->format->Rmask,
				  rz_src->format->Gmask,
				  rz_src->format->Bmask,
				  rz_src->format->Amask);
        SDL_FillRect(rz_dst,0,0xFFFF0000);

	}
      else
	{
	  /* Target surface is 8bit */
	  rz_dst =
	    SDL_CreateRGBSurface (SDL_SWSURFACE, dstwidth, dstheight, 8, 0, 0,
				  0, 0);
        SDL_FillRect(rz_dst,0,0xFF000FF0);
	}

      /* Lock source surface */
      SDL_LockSurface (rz_src);
      /* Check which kind of surface we have */
      if (is32bit)
	{
	  /* Call the 32bit transformation routine to do the zooming (using alpha) */
	  zoomSurfaceRGBA (rz_src, rz_dst, smooth);
	  /* Turn on source-alpha support */
	  SDL_SetAlpha (rz_dst, SDL_SRCALPHA, 255);
	}
      else
	{
	  /* Copy palette and colorkey info */
	  for (i = 0; i < rz_src->format->palette->ncolors; i++)
	    {
	      rz_dst->format->palette->colors[i] =
		rz_src->format->palette->colors[i];
	    }
	  rz_dst->format->palette->ncolors = rz_src->format->palette->ncolors;
	  /* Call the 8bit transformation routine to do the zooming */
	  zoomSurfaceY (rz_src, rz_dst);
	  SDL_SetColorKey (rz_dst, SDL_SRCCOLORKEY | SDL_RLEACCEL,
			   rz_src->format->colorkey);
	}
      /* Unlock source surface */
      SDL_UnlockSurface (rz_src);
    }

  /* Cleanup temp surface */
  if (src_converted)
    {
      SDL_FreeSurface (rz_src);
    }

  /* Return destination surface */

  return (rz_dst);
}

/*

 zoomSurface()

 Zoomes a 32bit or 8bit 'src' surface to newly created 'dst' surface.
 'zoomx' and 'zoomy' are scaling factors for width and height. If 'smooth' is 1
 then the destination 32bit surface is anti-aliased. If the surface is not 8bit
 or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly.

*/

#define VALUE_LIMIT	0.001

SDL_Surface *
zoomSurface (SDL_Surface * src, double zoomx, double zoomy, int smooth)
{
  SDL_Surface *rz_src;
  SDL_Surface *rz_dst;
  int dstwidth, dstheight;
  int is32bit;
  int i, src_converted;

  /* Sanity check */
  if (src == NULL)
    return (NULL);

  /* Determine if source surface is 32bit or 8bit */
  is32bit = (src->format->BitsPerPixel == 32);
  if ((is32bit) || (src->format->BitsPerPixel == 8))
    {
      /* Use source surface 'as is' */
      rz_src = src;
      src_converted = 0;
    }
  else
    {
      /* New source surface is 32bit with a defined RGBA ordering */
      rz_src =
	SDL_CreateRGBSurface (SDL_SWSURFACE, src->w, src->h, 32, 0x000000ff,
			      0x0000ff00, 0x00ff0000, 0xff000000);
      SDL_BlitSurface (src, NULL, rz_src, NULL);
      src_converted = 1;
      is32bit = 1;
    }

  /* Sanity check zoom factors */
  if (zoomx < VALUE_LIMIT)
    {
      zoomx = VALUE_LIMIT;
    }
  if (zoomy < VALUE_LIMIT)
    {
      zoomy = VALUE_LIMIT;
    }

  /* Calculate target size and set rect */
  dstwidth = (int) ((double) rz_src->w * zoomx);
  dstheight = (int) ((double) rz_src->h * zoomy);
  if (dstwidth < 1)
    {
      dstwidth = 1;
    }
  if (dstheight < 1)
    {
      dstheight = 1;
    }

  /* Alloc space to completely contain the zoomed surface */
  rz_dst = NULL;
  if (is32bit)
    {
      /* Target surface is 32bit with source RGBA/ABGR ordering */
      rz_dst =
	SDL_CreateRGBSurface (SDL_SWSURFACE, dstwidth, dstheight, 32,
			      rz_src->format->Rmask, rz_src->format->Gmask,
			      rz_src->format->Bmask, rz_src->format->Amask);
    }
  else
    {
      /* Target surface is 8bit */
      rz_dst =
	SDL_CreateRGBSurface (SDL_SWSURFACE, dstwidth, dstheight, 8, 0, 0, 0,
			      0);
    }

  /* Lock source surface */
  SDL_LockSurface (rz_src);
  /* Check which kind of surface we have */
  if (is32bit)
    {
      /* Call the 32bit transformation routine to do the zooming (using alpha) */
      zoomSurfaceRGBA (rz_src, rz_dst, smooth);
      /* Turn on source-alpha support */
      SDL_SetAlpha (rz_dst, SDL_SRCALPHA, 255);
    }
  else
    {
      /* Copy palette and colorkey info */
      for (i = 0; i < rz_src->format->palette->ncolors; i++)
	{
	  rz_dst->format->palette->colors[i] =
	    rz_src->format->palette->colors[i];
	}
      rz_dst->format->palette->ncolors = rz_src->format->palette->ncolors;
      /* Call the 8bit transformation routine to do the zooming */
      zoomSurfaceY (rz_src, rz_dst);
      SDL_SetColorKey (rz_dst, SDL_SRCCOLORKEY | SDL_RLEACCEL,
		       rz_src->format->colorkey);
    }
  /* Unlock source surface */
  SDL_UnlockSurface (rz_src);

  /* Cleanup temp surface */
  if (src_converted)
    {
      SDL_FreeSurface (rz_src);
    }

  /* Return destination surface */
  return (rz_dst);
}

#ifdef WIN32
 /* For DLL building under VC6 */
BOOL APIENTRY
DllMain (HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
  switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
      break;
    }
  return TRUE;
}
#endif
